Ciphering device



May 1951 J w. SMITH 2 2,554,507

CIPHERING DEVICE Filed Aug. 11, 1947 D-C'SOURCE E 3) '6 Z3 @EU gmccc mg 5 PO. u,

JOHN W. SMITH INVENTOR.

"ATTORNEY Patented May 29, 1951 t STATES FATENT OFFE QE CIPHERING DEVICE tion of Delaware Application August 11, 1947, Serial No. 767,996

to a distant point. At the reproducing end the electrical variations representing the subject copy density variations are recorded in a manner to produce a'faithful reproduction of the original copy. Almost any type of graphic material consisting of pictures, text, etc., may be reproduced by facsimile methods. Facsimile is useful in military operations since a great variety of necessary 1 Claim. (01. 88-24) material may be transmitted from point to point.

Maps are one example of useful types of material which may be reproduced at a distant point for military purposes. However, transmission of facsimile signals over radio channels may give an enemy an opportunity to intercept and reproduce the' material being transmitted. For this reason it is often highly important that a method be employed which will render the transmission secret.

The present invention concerns devices useful in rendering facsimile transmission secret. In the patent application of John V. L. Hogan et al. entitled Graphic Privacy System," filed June 4, 1943, and bearing Serial Number 489,654, now Patent No. 2,437,255, issued March 9, 1948, a device has been described for reproducing graphic material a small area at a time in which the small areas are mixed according to a complex mechanically determined code. The original subject copy is attached to a rotatable drum and an optical system transfers a predetermined area of; the copytoa second drum carrying alight sensitivesheet The device of the present invention operates on the same general principle but provides simplified control devices for creating the coded mixing of the areas which are transferred from the subject copy to form the enciphered reproduction. Furthermore, the device of the present invention automatically creates a mechanically determined code of a high order of complexity. The subject copy is scanned in strips and a stroboscopically operated light source instantaneously transfers small areas from this strip to new locations on the recording sheet mixed according to a code determined by a number of coding switches.

One object of the present invention is to provide a device for automatically enciphering graphic material.

Another object of the present invention is to provide a device for enciphering graphic material at a relatively high rate of speed. I

Still another object of the present invention is to provide a device for enciphering graphic material in which the coding may be readily changed.

A further object of the present invention is to provide a device for automatically enciphering graphic material according to a highly complex coding system.

A still further object of the present invention is to provide a relatively simple device which is capable of automatically enciphering graphic material according to a complex predetermined code.

These and other objects of the present invention will be apparent from the detailed descrip tion of the invention given in connection with the figure of the drawing.

The drawing shows a diagram of one form of the present invention.

The drawing shows a motor I, turning copy drum I I, through shaftsZ, I, and 9 and gear box 8. Gear box 8 is a speed reducing gear arrange ment having'a ratio of four to one so that drum I I turns at one quarter the speed of motor shaft I. In the device shown, the circumference of the copy drum II is to be considered as divided into four parts solely for purposes of i1lustration; In most cases the circumference will be divided into a large number of parts, of the order of fifty to one hundred. The ratio of gear box .8 will, in general, be equal to the number of parts into which the circumference is divided. The original copy is attached to the surface of drum I I and is transferred a small area at a time to the surface of drum 25. In order to effect the transfer, lamp house 2| is provided. A high speed flash lamp, not shown, is housed within lamphouse 2i and is supplied with energy over wires 21 and 28. Light from the high speed lamp is focused on the surface of drum II by means of lens system 23. The illuminated area on drum I I is transferred to photo-sensitive paper or film mounted on drum 25, by means of lenses 22 and 24 also carried by lamp-house 2I. Drum I l is provided with a shaft extension M carrying switch rotor 20 which makes successive contacts with switch points I6, I'I, I8 and I9 of switch I5. Drum 2'5 carries a shaft extension 43 with switch arm i6 which makes successive contacts to such switch points as 45 on switch body 44. Drum I I is rotated continuously by motor I while drum 25 is moved a step at a time by ratchet motor 30-32.

In order to transfer the image of a predetermined area from drum H to drum 25, the strobctron lamp in lamp box 2| is fired. For each position of drum 25 the strobotron firing circuit is completed through switches 44 and i5 through associated arms and contacts. The par.- ticular contact which completes the circuit depends upon the position of key-block switches 58 and G5. The manner in which the key switches are connected together and the manner inwhich they are rotated determines the particular sequence of mixing of the areas as they are transferred from drum H to drum 25. The various switches in the drawing are shown-in a position to complete the strobotron power and firing circuit. The impulse to fire the strobotron is generated by the passage of magnetic slug 4 in disc 3 between the poles of magnet 5. Coil 6 picks up this impulse which it passes tothe strobotron power firing circuit 26 whenever the coil circuit, on one end, is completed to ground. Tracing the circuit from coil ii zto ground, it passes through the contact arm 2:2, to switch contact 436, toblock or contact 59 of switch 56, through an. interconnecting wire on switch 5.5 to the lead it: going to contact 69: on key. switch 65, through an interconnecting wire 68 to contact 66, then through an interconnecting wire iii to contact 55 on switch it and then. through contact arm it to ground (3'. For each position of drum 2'5, drum H completes one revolution, scanning the contacts on v.itch 55. A predetermined area. from. drum i i is translt'erred to drum 25 corresponding to the drum osition on. contact" arm 20. Upon the compietion of each revolution of drunr H cam' t9 on shaft s closes contacts i2 and I3, completing the circuit between coil 34' and D. C. source 35. When this circuit is completed solenoid plunger 32 is pulled down against spring 33-, and tooth 3! of the ratchet motor 39*32', causing" drum 25 to rotate to a new position correspondingto the distance between the contacts on switch id. With drum 25 at this new position drum ll continues to rotate and the circuit to the strobotron is completed at a new position of contact arm 28, transferring another area from drum H to drum 25. This process is continued until drum 25 has made one complete revolution and a complete strip of graphic material has been transferred. from drum ii to drum 25, each sectional area of which has been. mixed according to a predetermined code.

Upon the completion of the rotation of drum 25, the so ch arm 46 closes the circuit to contact 9,5 to the lamp transporting means 86, causing the lamp house to move an amount equal to the width oi one column of copy to be transferred. The process above described for transferring nin a strip or column of' copy is repeated, upon completion of which the lamp house again moved to a new position. This process is continued until the complete copy on drum H is transferred, in mixed order, an elemental area at a time, to drum 25. The enciphered copy latent image on drum 25 is developed and fixed and may then be utilized in a standard facsimile transmission system to send an enciphered copy to a distant point. The copy is deciphered by a device similar to the one described which reverses the process herein described.

Each time lamp house 2! is shifted to a new position, the next contact bearing against rod ll, such as contact 49', drops into slot 48 opening the circuit between contacts 49 and 50. The circuit previously opened is closed, closing the circuit through ratchet motor coils 54 and 14, causing ratchet motors 5| and I! to operate. These ratchet motors operate until the circuit, through their respective coils and switches S2'i819, comes back to the open contact 49'5fl'. The particular sequence of the circuit is determined by the interconnection and transposition block switch 19 which may be changed to change the code arrangement of the system. This stepping of ratchet motors 5| and ll changes the sequence of connections between switches l5 and 44 since it changes the position of switches 56- and' 65.

In orderto start the operation of the system, switch 38.. is: operated closing contacts 363'|39, thereby energizing the various ratchet motors. At the end of the scanning process the last contact on rod 41 opens, releasing switch 38 by deenergizing coil. 40. The process may be stopped at. any time by pressing switch. ll-42;

' While a system has: been described for, dividing the copyinto. four rectangles in each of five strips, generally; a much larger number of; divisi'ons will be made since the degree. of secrecy attained will bea. function of the number of divisions. -In practice to 100; columns: divided, into 50 to 100 parts each.v have been utilized accordingto the present invention- The number of con.- tacts-and interconnectionsof the various switches is increased accordingly. It will beev-identthat the number of difl'erent combinations of element positions in the encipheredcopy increasesrapidly with the number of elements and hence the degree of secrecy attained.

While onlyone embodiment of the present invention' has'been shown and described, many variations will be apparent to those skilled in the art within the spirit and-scope of the invention as set forth, in the-appended claim.

What is claimed is:

In a device for making a scrambled copy of graphic material, the combination of, a first-rotatabl'e drum for holding copy to be scrambled,

tem in a predetermined mutual relationship,

means for energizing saidlamp in a sequence of predetermined mutual positions of said drums and said optical system to transfer scrambled image areas from the first said drum tothe second said drum, a plurality of series connected keyblock switches for determining the instant of energizing of said lamp with relation to said mutual positions, and means for shifting the positions of said key-blocks upon each energizing of said lamp.

JOHN W. SMITH.

REFERENCES CITED The followingv references are: of record in the file of this patent:.

UNITED STATES PATENTS Number Name Date 1,355,370 Tremor Apr. 26, 1932 2,364,188 Bryce Dec. 5, 1944 2,425,616 Hallborg Aug. 12, 1947 

